1. Field of the Invention
The present invention relates to an information processing apparatus such as a notebook personal computer (hereinafter referred to as a notebook PC). Particularly, the present invention relates to a casing structure of an information processing apparatus.
2. Description of Related Art
Nowadays, notebook PCs are becoming increasingly widespread, and in addition to various functions, notebook PCs with various forms are available on the market.
Notebook PCs are driven generally by electricity supplied from a rechargeable battery. The battery is detachable from a predetermined position in a notebook PC. Some recent notebook PCs include a detachable storage medium such as for example a hard disk drive (hereinafter referred to as an HDD) and a silicon disk drive built therein. For example, an HDD that is detachable from the notebook PC mainly is replaceable due to deterioration and damage, and mainly used for an increase in storage capacity and for a data transfer.
FIG. 7 is a perspective view of a conventional notebook PC. The notebook PC shown in FIG. 7 is configured of a first casing 101 provided with a keyboard 103 and a central processing unit (CPU), and a second casing 102 provided with a liquid crystal monitor 104. The first casing 101 and the second casing 102 are supported pivotally by a hinge mechanism 105. Herein, the state of the notebook PC as shown in FIG. 7 is defined as a first state, and in a state defined as a second state, the liquid crystal monitor 104 is facing the keyboard 103 by allowing the second casing 102 to pivot in the direction indicated by arrow A from the first state.
FIG. 8 is a rear elevation view of a notebook PC in the second state. As shown in FIG. 8, a battery unit 106 and a cover 107 are disposed at a rear face 101b (rear face 101b is the opposite face to a front face 101a as shown in FIG. 1) and a bottom face 101c of a notebook PC. The battery unit 106 includes therein a rechargeable battery capable of supplying electricity to the notebook PC. The cover 107 is disposed so as to cover an HDD disposed therein. A side face 106a of the battery unit 106 and a side face 107a of the cover 107 are facing each other with a miniscule gap interposed therebetween.
On the bottom face 101c of the first casing 101, foot portions 108 formed of an elastic material such as rubber are disposed to protect the notebook PC from, for example, impact. The foot portions 108 are disposed in the proximity of each of the four corners on the bottom face 101c. 
Patent Document 1 (JP 2003-167644A) discloses a configuration of a notebook PC having foot portions on the bottom face thereof. Patent Document 2 (JP 2007-164884A) discloses a configuration of a mobile phone in which the battery and the hard disk drive are slid along the plane so as to be disposed in a non-overlapped manner.
However, as shown in FIG. 8, when the cover 107 and the battery unit 106 are disposed side by side along the plane of the bottom face 101c of the first casing 101, along the border portion Y where the cover 107 and the battery unit 106 face each other, rigidity of the first casing 101 in the thickness direction thereof is insufficient. Therefore, when the notebook PC is dropped accidentally on the floor or the like, or when a strong pressure is applied on the upper face 101e of the first casing 101 or to the rear face 102a of the second casing 102 in the direction indicated by arrow Z, as shown in FIG. 9, flexing possibly is caused along border portion Y. Under such conditions, a problem arises, i.e., the first casing 101 and its built-in electric circuit board may be damaged.